Temperature Scales
If two objccts are placed in contact with one another, thermal energy may flow from one object to the other one. Temperatureis the quality that determines the direction in which thermal energy flows — it flows from the object at higher temperature to the object at lower temperature.
Temperatures are ordinarily measured by means of a thermometer, such as the ordinary mercury thermometer, consisting of a quantity of mercury in a glass tube. The temperature scale used by scientists is the centigradeor Celsius scale; it was introduced by Anders Celsius (1701— 1744), a Swedish professor of astronomy, in 1742. On this scale the temperature of freezing water saturated with air is 0eC and the temperature of boiling water is 100°C at 1-atm pressure.
On the Fahrenheit scale, used in everyday life in English-speaking countries, the freezing point of water is 32°F and the boiling point of water is 212°F. On this scale the freezing point and the boiling point differ by 180°, rather than 100° of the centigrade scale. The Fahrenheit scale was devised by Gabriel Fahrenheit (1686-1736), a natural philosopher who was bom in Danzig and settled in Holland. He invented the mercury thermometer in 1714; before then, alcohol had been used as the liquid in thermometers. As the zero point on his scale he took the lowest temperature he could obtain, produced by mixing equal quantities o f snow and ammonium chloridc. His choice of 212° for the boiling point of water was made in order that the temperature of his body should be 100°F. The normal temperature of the human body is 98.6°F; perhaps Fahrenheit had a slight fever while he was calibrating his thermometer.
To convert temperatures from one scale to another, you need only remember that the Fahrenheit degree is m/m or V9 of the centigrade degree, and that 0°C is the same temperature as 32°F.
Another absolute scale, the Rankine scale, is sometimes used in engineering work in the English-speaking countries. It uses the Fahrenheit degree, and has 0°R as the absolute zero.
Mashq 3. Matnning asosiy tarkibini bir nechta jumlalarda ko'rsating.
Mashq 4. Matnning rejasini tuzing.
Mashq 5. Jumlalarni o'qing va matn mazmuniga mos kelishini ayting. Agar yo'q bo'lsa, ularni tuzating.
1. Temperature determines the direction in which thermal energy flows when the two objects are in contact. 2. Thermal energy flows from the hotter object to the colder one. 3. Temperature is measured by means of thermometers using different temperature scales. 4. The inventor of the Fahrenheit scale was German. 5. Fahrenheit devised alcohol thermometer.6. Only the Fahrenheit scale is used in the English-speaking countries.7. The temperature of the boiling water is 100 degrees centigrade. 8. The inventor of the centigrade scale was an outstanding physicist.
Mashq 6. Harorat qiymatini bir shkaladan ikkinchisiga qanday o'tkazishni tasvirlaydigan matnni toping va rus tilidagi jumlalarga tarjima qiling
Do'stlaringiz bilan baham: |